The present invention relates to a mass spectrometer and a method of mass spectrometry. According to the preferred embodiment a time of flight acquisition system is provided.
As will be understood by those skilled in the art, there is uncertainty in the recorded times of ions which are detected by a Time of Flight mass analyser due to sampling both of the accelerating pulse and of the detector signals. The resulting uncertainty amounts to the sampling interval and is due to asynchronicity of the sampling clock with the time of flight acquisition system.
For a single flight of ions the timing uncertainty results in an error in the recorded or determined mass or mass to charge ratio of the detected ion. Where many flights are integrated then the error decreases with the square root of the number of flights being integrated but the uncertainty nonetheless results in a broadening of the integrated detected signal and an apparent reduction in the system resolution.
It is known to attempt to initiate the accelerating pulse from the sampling clock. However, this approach suffers from the problem of introducing jitter in the accelerating event and this jitter is equivalent to timing uncertainty. The known approach does not remove the asynchronicity of the detected signal because the time of arrival is highly unlikely to be an exact integral multiple of the sampling time. As a result, the known arrangement suffers from the problem of systematic timing errors which does not reduce as more flights are integrated.
It is therefore desired to provide a method of mass spectrometry and a mass spectrometer which does not suffer from the above mentioned problems.